Rotary die cutters are used commonly on high speed rotary printing presses such as the Mark Andy or Webtron presses to manufacture labels The diameter of the die roll is critical It must match the spacing dictated by the labels to be cut. The gear driving the roll must have a pitch matched to the web speed and this is usually accomplished by a direct mechanical gear drive Each size of label must have its own roll and bringing the machine into register is a somewhat complicated operation requiring usually the services of a skilled--thus expensive--setup person and operator.
A conventional rotary die cutter geared to the speed of the web cannot be timed to correct printing inaccuracies, for example, to die cut on a web that has been printed off-line It cannot be timed to intercept the moving web at a precise point. It is designed for high speed operation and change-over can require considerable effort.
Another method of die cutting labels is to use an intermittent flat bed steel rule die which reciprocates in an up and down motion to cut the labels The web must be stopped while cutting is occurring. Again, to secure uniform cutting across the width and depth of the die requires a skilled setup.
A flat bed die must contact the pressure sensitive material over its entire surface simultaneously and therefore requires considerable pressure. Much time is required to adjust the die head or cutting table to obtain an even cut over the entire die cutting surface Because of the materials used, the die cutter has a limited work life and must be sharpened and/or replaced frequently.